Variable speed transmission



Oct. 21, 1941. B. H. LOCKE VARIABLE SPEED TRANSMISSION Filed Dec. 16,1940 2 Sheets-Sheet l M i M Oct. 21, 1941. B. H. LOCKE 2 VARIABLE SPEEDTRANSMISSION Filed Dec. 16, 1940 2 Sheets-Sheet 2 Patented Oct. 21, 1941.UNITED STATES PATENT OFFICE VARIABLE SPEED TRAN SIVIISSION Burton H.Locke, Lowell, Mass. Application December 16, 1940; Serial No. 370,266 3Claims. (c1 74-286) My invention relates to improvements in var-'permitting the use of relatively small frictional elements. To furtherminimize the torque imposed on the frictional elements, my improvedtransmission designs to utilize the said elements at the high speed endof the transmission where the torque is at the minimum.

A further object of my invention is to provide a mechanism whereinrelatively large reductions in speed intermediate the drive and drivenshafts can be obtained by the use of a minimum number of gears; and afurther object is to afford means to effect speed changes thereinj sothat the final transmitted motion can be minutely adjusted at 'will frommaximum to zero and then reversed as to direction.

. By using gears of a compact form and by permitting the use of smallfrictional parts, it is obvious that my improved transmission could bemade compact; could be produced at a relatively low cost and wouldafford a low maintenance anticipation.

In the accompanying drawings: Figure 1 is a plan view of my improvedvariable speed transmission.

Figure 2 is a sectional side elevation of same taken at 2-2 on Figure 1.

Figure 3 is an end elevation of same taken at the end of the drive shaftand with the end flange removed.

My improved variable speed transmission comprises a casing l0,constructed of a center section II and end flanges l2 and I3 fastenedthereto by means of cap screws l4. Center section H has suitable feeti5, at the bottom portion thereof, with bolt holes Hi to be utilized inmounting the transmission to a base or other anchorage. The casing isgenerally partially filled with oil to lubricate the interior gearingand bearings which is common practice in the art. A drive shaft [1,generally rotating at high speed, is journaled in bearing 18 supportedin end flange l2, and grooves l9, which generally contain felt,are-provided to prevent oil escaping from the casing. A driven or lowspeed shaft 20 is .journaled in bearing 2! supported in sleeve 22 whichis secured in end flange 13 by cap screws 23. Grooves driven shaft 20. Adisc 3| is mounted on driven 24 are provided to prevent oil fromescaping from the casing around shaft 20. The inner end 25 of driveshaft I1 is journaled in a bearing 26 supported in the inner end 21 ofdriven shaft 29. A sun gear 28 is mounted on drive shaft l1 and securedthereto by key 29, and a thrust collar 30 is provided intermediate .saidgear and the shaft, 20 and secured thereto by key 32, said disc 3|carries a plurality of planet gears 33 which mesh with sun gear 28 andare rotatively mounted on studs 34 integrally secured in said disc atequal circumferential spacings around said sun gear. Bushings 35, andthrust collars 36, are provided to'form bearings for the planet gears33. Planet gears 33 mesh with an internal gear 31 rotatively mounted'onsleeve 22 and a bearing bushing 38 is provided. A worm gear 39 issecured on the hub 40, of internal gear 31, by

key 4| and meshes with a worm 42 secured to a shaft 43 by key 44. Shaft43 is journaled in bearings 45 mounted in bosses 46 provided on centersection II of easing I0.

Shaft 43 is generally mounted perpendicular to the axis of worm gear 39to position worm 42 most effectively to cooperate in checking therotation of said worm gear to accomplish an objective hereinafterdescribed. One end 41, of shaft 43, terminates within its bearing 45 andthe bearing opening is sealed by means of cap 48 secured by cap screws49. The other end 50, of shaft 43, extends outside of casing l0 for thepurpose of receiving variable speed mechanism hereinafter described andgrooves 5| are provided to prevent oil escaping from the casing.

A spiral'gear 52 is secured on drive shaft l1, adjacent to bearing 18,by key 53 and a spacing sleeve 54 is provided intermediate said spiralgear and sun gear 28 to insure said gears being held in proper spacedrelationship on said shaft. Spiral gear 52 meshes with a similar spiralgear 55 secured on a shaft 56 by key 51. Shaft 56 is journaled inbearings 58 mounted in bosses 59 provided on center section I l ofeasing l9. Shaft 56 is generally mounted parallel to shaft 43 tofacilitate the two said shafts being connected by variable speedmechanism to be described. Thrust collars 69 are secured to shaft 56.byset screws 6| to retain said shaft from endwise movement, otherwise theconstruction of shaft 56 is like shaft 43.

A pair of cone pulleys 62 and 63 are mounted at the outer end 64 ofshaft 56 and a similar pair of pulleys 65 and 66 are mounted at theouter end 50 of shaft 43 for the purpose of. cooperating boss 59 oncenter section II of casing I and when said hand wheel is manipulated itwould .shift pulley 63 laterally, thereby changing the effectivediameter of pulleys 62 and 63 in cooperation with V-belt 61. A ballthrust bearing 12 is provided intermediate pulley 63 and handwheel tominimize friction therebetween when the pulley is rotating.

Cone pulley 85 is secured integral to shaft 43 by means of pin 13 andpulley 66 is mounted to rotate with shaft 43 by key 14 but is free tomove laterally thereon and also free to slide within pulley 65. Sleeveportion 15 of pulley 66 has a slot 16 cut therein to clear pin 13 topermit the lateral movement of said pulley. The end portion 11 of sleeve15 has threaded engagement with adjusting nuts 18 and a compressionspring 19 is provided intermediate said nuts and pulley 65. Spring 19affords pulleys 65 and 66 being in resilient contact with V-be1t 61which, obviously, will retain proper operating tension on the belt atall times as pulleys 62 and 63 are adjusted. It is obvious that pulleys55 and 66 will be brought nearer together by spring 19 whenever V- belt61 is released by pulleys 62 and B3 shifting apart. Conversely, wheneverpulleys 62 and 63 are adjusted toward each other tension will be set upin the V-belt which would force pulleys 65 and 66 apart against theaction of spring 19. Spring 19 can be adjusted to a proper operatingcondition by means of adjusting nuts 18. Therefore, the relative speedsof shaft 56 and 43 can be readily changed by manipulation of handwheel10 as this would effect a change in the relative operating position ofV-belt 61 on the cone pulleys thereby effecting changes in the effectivediameters of said pulleys. secured to the end 50 of shaft 43 by means ofpin SI, for the purpose of insuring retainance of the cone pulleys onthe shaft.

In operation it is essential that worm gear 39 be driven in thedirection of the torque imposed on same by the operation of thetransmission, therefore, the hand of threads on worm 42 and worm gear 39should be constructed in cooperation with the hand of teeth on spiralgears 52 and .55 to afford such a rotation. Worm 42 is generally madewith a plurality of threads to Collar 80 is y afford proper angle, orlead, to the threads for I the purpose of permitting worm 42 to berotated by worm gear 39 substantially at the point when a normal torqueis imposed on said worm gear,

resulting 'by the transmission being operated under a normal load. Underthis condition the pull on V-belt 6'! would be substantially zero. Whena subnormal load is being transmitted it -is obvious that there would bea relatively light pull on one side of the V-belt to assist the lessenedtorque pressure to drive the worm. Conversely,

under an abnormal transmitted load a relatively would permit the use ofrelatively small variable speed equipment which would afford compactnessand low cost of construction and maintenance. To further minimize thetorque imposed on the variable speed equipment same is positioned at thehigh speed side of the transmission where the speed is generally highand the torque resultantly low.

Those skilled in the art of transmissions are aware that ifthe drivingshaft of a planetary transmission, such as shaft ll of the transmissionshown, is rotated, the planet gears 33 will rotate and will transmitrotation to the internal gear 31. It is also well known that by holdingthe internal gear while the driving shaft is rotated, the planet gearswill travel around the sun gear -28 and will thus cause rotation of thedriven shaft 20 in the direction of the drive shaft I1. Also it is wellknown that if the internal gear is driven or permitted to rotate atvarious speeds the rotation of the driven shaft will. be effectedaccordingly, and also the driven rotationof the internal gear could besuch as to cause the driven shaft to be rotated in the reverse directionto the drive shaft. Therefore, it is obvious that the rotation of thedriven shaft 20 of the transmission shown can be minutely adjusted fromthe maximum permitted speed in the direction of the rotation of thedriving shaft ll down to zero and then up to its maximum permitted speedin the reverse direction by manipulation of handwheel 10.

Further, it is 'well known to those skilled in the art of transmissionsthat when large reductions in speed are required a plurality ofplanetary reduction sets are utilized in alignment and in suchtransmissions the driven member of the first set is the driving memberof thesecond set, and so on, with the driven member of the last settransmitting the final motion. Therefore, it is obvious that one or more'sets of reduction gears, of the planetary former of other conventionalform, could be utilized proceeding my variable speed transmission in anextended casing where further reductions in speed were required, withoutdeparting from the spirit of the invention.

It is obvious that other forms of planetary gearing, and also forms ofso called differential gearing, that have three main parts or portionscould be harnessed in the manner set forth by applicant to achievesimilar results. Also other conventional forms of variable speed drivecould be utilized in place of that shown. However, for reason ofbrevity, applicant has only shown one formof equipment, this being themost successful form of equipment in present day use. Therefore, I donot wish to be confined to, the exact details shown as same aresusceptible of modification without departing from' the spirit or scopeof the invention which is broadly set forth in the following claims.

The phrase at the point of normal operating torque is used in thisapplication to mean at the point when the transmission is operatingunder a normal load and at normal or mean output speed. Inorder toeffect a balance to the recession member at this point, it is obviousthat the helix angleof worm 42 and worm gear 39 would have to be such asto meet the coefliclent of friction of the said helix plus the journalfriction encountered at this point.

I claim as my invention:

1. A variable speed transmission comprising a, casing, a drive anddriven shaft, and gearing intermediate said shafts, said gearingcomprising three main parts or portions, one portion being integral tosaid drive shaft, another portion being integral to said driven shaft,and the third portion being rotatively mounted to recede to effectchanges in speed intermediate the drive and driven shafts, and means tocontrol the recession of said third portion from'said drive shaftcomprising two parts, one of said parts being a balancing meanscomprising a worm gear integral with said third portion, and a wormmounted to cooperate therewith, said gear and worm having proper helixangle to efiect a balance to the said recession substantially at thepoint of normal operating torque, the other of said parts comprising anadjustable V-belt drive operated from said drive shaft to control therotation of said worm for the purpose of controlling the said recession.

2. A variable speed transmission comprising a casing, a drive, anddriven member, and gearing intermediate said members, said gearingcomprising three main parts or portions, one portion being driven fromsaid drive member, another portion transmitting the motion to saiddriven member, and the third portion being rotatively mounted to recedeto effect changes in speed intermeans to control the recession of saidthird portion. from said drive member comprising two parts, one of saidparts being a balancing means comprising a worm gear integral with saidthird portion, and a worm mounted to cooperate therewith, said gear andworm having proper helix angle to efiect a balance to the said recessionsubstantially at the point of normal operating torque, the other of saidparts comprising an adjustable V-belt drive operated from said drivemember to control the rotation of said worm, for the purpose ofcontrolling the said recession.

3. Means to control the recession permitted in variable speedtransmissions to efiect changes in speed intermediate the drive anddriven members, said means comprising two parts, one of said parts beinga balancing means comprising a worm gear integral with the recessionmember, and a worm mounted to cooperate therewith, said gear and wormhaving proper .helix angle to efiect a balance to the said recessionsubstantially at the point of normal operating torque, the other ofmediate the drive and driven members, and

said parts comprising an adjustable V-belt drive operated from saiddrive member to control the rotation of said worm, for the purpose ofcontrolling the said recession.

BURTON H. LOCKE.

